void Bin_add(int addend1[], int addend2[], int sum[],
      int max_bit) {
   int carry = 0;
   for (int bit = 0; bit < max_bit; bit++) {
      temp = addend1[bit] + addend2[bit] + carry;
      sum[bit] = temp % 2;
      carry = temp/2;
   }
}
